如何直接调用 servlet 以在 JSP 站点上显示输出？

Question

我的问题是如何让它工作，以便我运行 Eclipse JEE 中的 servlet 显示一个 jsp 站点，其中包含一个数据 table 作为结果？通常，整个页面都是空的，或者我只看到 table 列名称。我同时连接到我的数据库，这应该不是问题。

这是 servlet。我想问题一定出在这里。

@WebServlet("/StudentListService") 
public class StudentListServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        ArrayList<Student> studentList = new ArrayList<Student>();

        try {
            StudentDAO studentDAO = new StudentDAO();
            studentList = studentDAO.getAllStudents();
            request.setAttribute("studentList", studentList);
            request.getRequestDispatcher("StudentList.jsp").forward(request, response);
        }

        catch (Exception e) {
            e.printStackTrace();
        }       
    }
}

这是相关的DAO方法。这个DAO我在之前的练习中用过class，应该可以的

public ArrayList<Student> getAllStudents() throws SQLException {
        ArrayList<Student> studentList = new ArrayList<Student>();
        Connection dbConnection = null;
    try {
        dbConnection = openConnection();

        String sqlText = "SELECT id, firstname, lastname, streetaddress, postcode, postoffice FROM Student";

        PreparedStatement preparedStatement = dbConnection.prepareStatement(sqlText);

        ResultSet resultSet = preparedStatement.executeQuery();

        while (resultSet.next()) {
            int id = resultSet.getInt("id");
            String firstName = resultSet.getString("firstname");
            String lastName = resultSet.getString("lastname");
            String street = resultSet.getString("streetaddress");
            String postCode = resultSet.getString("postcode");
            String postOffice = resultSet.getString("postoffice");

            studentList.add(new Student(id, firstName, lastName, street, postCode, postOffice));
        }

        return studentList;

    } catch (SQLException sqle) {
        throw sqle; // Let the caller decide what to do with the exception

    } finally {
        closeConnection(dbConnection);
    }

}

这是jsp。我不确定它是否正确，这只是其中的 jsp 部分，它应该显示在 html table.

中

<c:forEach items="${ studentList }" var="studentObject">
    <tr>
        <td><c:out value="${ studentObject.id}" /></td>
        <td><c:out value="${ studentObject.lastName }" /></td>
        <td><c:out value="${ studentObject.firstName }" /></td>
        <td><c:out value="${ studentObject.street }" /></td>
        <td><c:out value="${ studentObject.postCode}" /></td>
        <td><c:out value="${ studentObject.postOffice }" /></td>
    </tr>
</c:forEach>

Answer 1

要直接访问 servlet，请像这样从浏览器向您的 servlet 发出获取请求：localhost:8080/your-porject-name/StudentListService

如何直接调用 servlet 以在 JSP 站点上显示输出？

How to invoke the servlet direclty to show the output on the JSP site?

java

jsp

dao

servlets